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WORM_WCRY.J

August 10, 2017
 Analysis by: John Anthony Banes
 ALIASES:

Ransom:Win32/WannaCrypt.A!rsm (Microsoft); Win32:WanaCry-A (Avast); Ransom.Wannacry (Symantec)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via software vulnerability


This Worm does not have any backdoor routine.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

3,723,264 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 May 2017

Payload:

Drops files

Arrival Details

This malware arrives via the following means:

Autostart Technique

This Worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
Type = "16"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ImagePath = "{initial malware file path} -m security"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
DisplayName = "Microsoft Security Center (2.0) Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0\security
Security = {hex values}

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0\security

It starts the following services:

  • Service Name: mssecsvc2.0
    Display Name: Microsoft Security Center (2.0) Service
    Path to Executable: "{initial malware file path} -m security"

Backdoor Routine

This Worm does not have any backdoor routine.

Dropping Routine

This Worm drops the following files:

It executes the dropped file. As a result, malicious routines of the dropped file are exhibited on the affected system.

Other Details

This Worm does the following:

  • It scans the following to check for open port 445:
    • Randomly-generated IP addresses over the Internet
  • If it finds a host on the Internet with open port 445, it will attempt to exploit MS17-010 vulnerability to drop and execute a copy of itself to the remote host.
  • It uses the following file path for its dropped copies on the remote hosts.
    %Windows%\mssecsvc.exe
  • It checks for the presence of the file %Windows%\tasksche.exe. If the file exists, it will rename the file using the following name %Windows%\qeriuwjhrf.
  • It executes %Windows%\tasksche.exe with /i parameter.

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.584.04

FIRST VSAPI PATTERN DATE:

09 Aug 2017

VSAPI OPR PATTERN File:

13.585.00

VSAPI OPR PATTERN Date:

10 Aug 2017

Step 1

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 2

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 3

Remove malware/grayware files dropped/downloaded by WORM_WCRY.J. (Note: Please skip this step if the threats listed below have already been removed.)

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
    • mssecsvc2.0

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_WCRY.J. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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